1. Field
The present disclosure relates generally to aircraft and, in particular, to managing aircraft. Still more particularly, the present disclosure relates to a method and apparatus for a load estimation system for aerodynamic structures in aircraft.
2. Background
An aircraft is subjected to many different loads during the operation of the aircraft. For example, loads may be applied to different portions of the aircraft during takeoff, flight, landing, and other phases of flight. Identifying these loads may aid in the design, inspection, and maintenance of the aircraft with respect to operating at desired levels of performance and safety.
For example, an aircraft may encounter loads caused by wind during flight. These loads will affect different portions of the aircraft. For instance, loads caused by wind may be placed on a wing, an airfoil structure, an outer skin, a fuselage, or some other portion of the aircraft.
The wind encountered by the aircraft may be different at different altitudes. As a result, the wind at the various altitudes may generate different levels of force on the aircraft.
Often, aircraft may encounter wind gusts during flight. A wind gust is a burst of wind which happens randomly. This wind may have a speed that exceeds the lowest winds measured during some interval by some amount. In other words, a wind gust may be a burst of wind with a speed higher than measured for that particular location at the condition specified in a day.
Wind encountered by the aircraft also may take the form of a microburst. A microburst is a localized column of sinking air that may generate divergent and straight-line winds. As another example, the wind may take the form of wind shear. The wind shear may have vertical and horizontal components that place loads on the aircraft.
Loads occurring from these and other types of wind may cause fatigue in an aircraft and result in inconsistencies in the aircraft that affect the performance of the aircraft. The fatigue caused by these loads may occur over multiple instances of operation of the aircraft during the lifetime of the aircraft.
A determination of whether maintenance should be performed on an aircraft may be made by identifying the fatigue life left for the aircraft. In this illustrative example, a fatigue life of the aircraft is the number of stress cycles of a specified character that the aircraft experiences before undesired results occur. Fatigue is directly related to the loads that occur during the operation of the aircraft. The identification of fatigue from wind gusts may be more difficult than desired due to the random nature of wind gust. Therefore, it would be desirable to have a method and apparatus that take into account at least one of the issues discussed above as well as possibly other issues.